Basement Slab Strength

by John
(Atlanta, GA)

Q. I am thinking of building a storm shelter / safe room in my basement. The shelter will consist of cinder blocks reinforced with rebar and filled with concrete. The roof will be a poured reinforced concrete roof.

My question is: Will the basement slab floor support the weight? Or do I need to bust out the slab where the walls will go and pour reinforced footers?

A. Not knowing the thickness of the basement floor or what psi the concrete is makes this difficult to answer.

If the concrete is 6" thick and at least 3000 psi, it should support the weight. Unfortunately you will have to core drill some spots and have them tested to determine this.

I would recommend hiring an engineer and getting the concrete tested first. Breaking up the slab and pouring footings may need to be done, but I wouldn't do this unless the I knew for sure the basement floor wouldn't support the weight.